Although not exclusively, the present invention applies more especially to a patrol of aircraft. It is known that a patrol of aircraft, for example of fighters or military transporters, is composed of a lead aircraft, also called the leader, which is followed in flight according to a particular spacing (defined vertically, longitudinally and laterally) by one or more follower aircraft, also called wingmen. The relative flight between the lead aircraft and a follower aircraft may be performed:                a) either simply (and exclusively) on the basis of the judgment of the pilot of the follower aircraft, as a function of his direct vision of the lead aircraft;        b) or by way of a system of information and/or for aiding the pilot, such as an electronic system for aiding patrol flight.        
During a patrol flight, the aircraft follow one another while attempting, in particular, to constantly maintain one and the same longitudinal separation and one and the same lateral separation.
In situation b) above, these longitudinal and lateral separations are generally input by the pilot of the follower aircraft into the electronic system for aiding patrol flight. The values input are usually based on the experience of the pilot and on the customary procedures relating to a patrol flight.
However, such an implementation may engender certain problems. In particular:                if the pilot of the follower aircraft inputs a value of lateral separation that is too big, and if the lead aircraft performs a turn at high turning rate (on the side of the position of the follower aircraft), there is a risk that the follower aircraft may not be able to reduce its speed sufficiently to hold its relative position (taking into account said lateral separation value);        conversely, if the lead aircraft performs a turn on the opposite side with a high turning rate, there is a risk that the follower aircraft may not be able to accelerate sufficiently and hence hold its relative position.        